Hello Plugin World

Install:
1. Open RoboClient Control Panel.
2. Click PLUGINS.
3. Click Install folder.
4. Select this hello-world folder.
5. Click Run selected.

Plugin format:
- plugin.json describes id, name and entry script.
- main.py is run by RoboClient through PluginRuntime\Python312.
- RoboClient creates .venv inside the installed plugin folder.
